Apparatus for conductive drying loose

ABSTRACT

The apparatus includes a housing 1 accommodating inner and outer tubes 2 and 4, respectively, arranged concentrically relative to each other. Lower ends of the tubes 2 and 4 are connected by a flange 15 to a disk-type feeder 14 the flange and feeder having holes 13 and 21 through which the interior of a heating chamber 9 confined between the outer wall of the outer tube 4 and inner wall of the housing 1 communicates with interior 17 of the inner tube 2 and with the interior of the drying chamber 6 confined between the outer wall of the inner tube 2 and inner wall of the outer tube 4. Communicating with the drying chamber 6 are a charging hopper 7 and a discharging means 8 occupying the bottom part of the apparatus. Disposed in the wall of the housing 1 between the flange 15 and worm 5 of the outer tube 4 is a furnace 11 having a burner 12 and communicating with the interior of the heating chamber 9. In addition, the heating chamber 9 communicates with an exhaust pipe 10 of a suction means.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to processes associated with drying loosematerials, and more particularly to apparatus for conductive dryingloose materials.

2. Description of the Prior Art

There is known an apparatus (cf., USSR Inventor's Certificate No.918,752, Int. Cl. F 26 B 17/26, published 1982) for drying loosematerials including metal chips containing combustibles. The apparatuscomprises a drying chamber over which there is disposed a furnaceseparated from the drying chamber by a perforated partition wall, a heatexchanger for heating balls of a headpiece, a magnetic drum forseparating the headpiece balls from chip when the headpiece is heated tothe Curie point (for iron-carbon alloys the Curie point is +768° C.), anoscillating conveyer of the drying chamber, and an elevator forreturning the balls of the headpiece for reuse.

The material is heated and dried in the drying chamber upon contact withthe heated balls.

Oil evaporating from the material is subjected to reburning, the oilvapour entering through the perforated partition from the drying chamberto the furnace thereby providing extra heat utilized for heating theheadpiece balls in the heat exchanger.

One disadvantage of this prior art apparatus is that it cannot be usedoro drying fusible alloys having a melting point below the Curie point,heating to this point being necessary for separating the balls of theheadpiece from the magnetic drum.

The provision of the elevator for returning the balls of the headpiece,the magnetic drum, and oscillating conveyer in the drying chamberrequires consumption of an excessive amount of energy for the dryingprocess.

The apparatus is not capable of high thermal efficiency, since forremoving moisture and oil it is necessary to heat the material to atemperature of 200° C. to 350° C., whereas the headpiece must be heatedto 768° C. to be separated from the magnetic drum.

Waste gases escaping from the apparatus have the same high temperaturethus making the consumption of heat energy substantial. In addition, inthe course of conveying, the balls of the headpiece tend to lose heattransferring it to the elevator and oscillating conveyer.

There also is known a drum-type undirect heating apparatus for dryingloose materials (cf., West German Pat. No. 2,060,027, Cl. 82a 19/01,published 1973). The apparatus comprises a housing accommodating innerand outer tubes arranged concentrically relative to each other. Flue orwaste gas is withdrawn through the inner tube in a direction counter tothe travel path of the material in the drying chamber confined betweenthe walls of the inner and outer tubes, rigidly interconnected andcapable of being rotated by an external drive. The interior of theheating chamber is defined by a space between the walls of the housingand outer tube. Connected to the housing is a furnace communicating withthe heating chamber. A flare of the outer tube of the drying chamberextends to a discharge means and is connected to a device for suctioningthe vapours of moisture and oil. The drying chamber is isolated from theheating chamber by sealing members. The heating chamber communicateswith the interior of the inner tube through a flue chamber in turncommunicable with the discharge means. The inner tube of the dryingchamber is connected with a worm, which is in contact with the walls ofthe outer tube connected to a second worm.

Inherent in this prior art apparatus is a disadvantage in that oilevaporated from the material being dried is not utilized by secondaryburning, and therefore the potential heat from such oil vapours is notused as an additional source of energy, which makes this apparatus lessenergy efficient.

Another disadvantage resides in that the heating process is carried outwithout evacuation of the evaporated oil and moisture to result inoxidation and carbonization of the material.

In addition, the horizontal arrangement of the drum of the dryingchamber determines the large size of the apparatus.

SUMMARY OF THE INVENTION

The present invention is therefore directed toward the provision of anapparatus for conductive heating loose materials, in which a chamber fordrying the material and a heating chamber would be so constructed as toimprove the quality of drying and make the apparatus more fuel-efficientby utilizing combustion heat of the evaporate oil.

The aims of the invention are attained by an apparatus for conductivedrying loose materials comprising a housing accommodating outer andinner tubes arranged concentrically relative to each other, connectedtherebetween, and provided with worms at their outer walls, charging anddischarging means communicating with the interior of a drying chamberconfined between the outer wall of the inner tube and inner wall of theouter tube, a pipe of a suckoff means, and a furnace with a burnercommunicating with the interior of a heating chamber confined betweenthe outer wall of the outer tube and inner wall of the housing.According to the invention, in the vertical arrangement of the apparatusthe inner tube is capable of rotation, whereby the lower ends of theinner and outer tubes are connected by means of a flange to a disk-typefeeder provided with holes, the interior of the drying chambercommunicating with the interior of the heating chamber by way of theholes in the disk-type feeder, whereas the interior of the inner tubecommunicates with the interior of the drying chamber through the holesin the flange, the furnace being positioned between the flange and wormof the outer tube, the discharging means occupying the bottom part ofthe apparatus.

In order to prevent extensive contact of the material being dried withvapours of moisture and oil causing oxidation and carbonization, theinner tube is preferably provided with openings and has a burner mountedin the upper part thereof.

The invention ensures higher quality of drying and requires less fuel tobe consumed for the drying process.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in greater detail with reference toa specific embodiment thereof taken in conjunction with the sole FIGUREof the accompanying drawings illustrating an apparatus for conductivedrying loose materials.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The proposed apparatus comprises a housing 1 accommodating an inner tube2 with a worm 3 and an outer tube 4 with a worm 5, these tubes 2 and 4being arranged concentrically relative to each other and communicatingtherebetween. The interior of a drying chamber 6 confined between theouter wall of the inner tube 2 and inner wall of the outer tube 4communicates with charging and discharging means 7 and 8, respectively.The interior of a heating chamber 9 confined between the outer wall ofthe outer tube 4 and inner wall of the housing 1 communicates with anexhaust pipe 10 of a suction means. A furnace 11 has a burner 12, and issecured in the wall of the housing 1. The interior of the drying chamber6 communicates with the interior of the heating chamber 9 by way ofholes 13 provided in a disk-type feeder 14 of a flange 15 connecting thelower ends of the inner and outer tubes 2 and 4. The discharging means 8has an adjustable plunger 16.

Interior 17 of the inner tube 2 communicates with the drying chamber 6by way of openings 18 provided in the tube 2. Each such opening 18 has ashield 19. A burner 20 is further provided in the upper part of theinterior 17 of the tube 2.

The flange 15 has holes 21 to communicate the interior 17 of the tube 2with the heating chamber 9, which accommodates a thermometer 22.

The inner tube 2 and disk feeder 14 are connected to a rotation drive23.

The herein proposed apparatus for feeding loose materials operates inthe following manner.

Moist loose material is placed in the charging means or hopper 7 to beadmitted to the chamber 6, and the rotation drive 23 is energized torotate the inner tube 2 with the worm 3 and disk feeder 14. Then thesuction means for evacuating gases through the pipe 10, and burners 12and 20 are actuated in succession. An underpressure or vacuum isproduced by the suction means in the heating chamber 9 and in theinterior 17 of the tube 2 communicating therewith through the holes 21.

Fuel combustion products generated by the burner 20 move from thisburner 20 along the interior 17 of the tube 2, pass through the holes21, and enter the heating chamber 9, where they are mixed withcombustion products produced by the burner 12, after which the thusmixed combustion products move upwards along the helical guide of theworm 5 toward the pipe 10.

The downward travel of the fuel combustion products from the burner 20acts to vigorously heat the surface of the inner tube 2 and worm 3 forthe heat to be transferred therefrom to the loose material movingdownwards by the worm 3.

In the course of the upward travel of the combustion products thehelical guide of the worm 9 and outer tube 4 tend to be vigorouslyheated. The heat is transferred therefrom to the material being heated.During its movement in the drying chamber 6 the material is heated ontwo sides, whereby moisture and oil present in the material areevaporated, and the vapours are evacuated through the openings 18 in thecourse of the drying process. The oil vapours tend to partially burn inthe flame of the burner 20. The remaining part of the oil vapours movesfrom the interior 17 through the holes 21 in the flange 15 to theheating chamber 9 to be burned in the flame of the burner 12. The flameof this burner 12 also burns the oil vapours entering from the dryingchamber 6 through the holes 13.

According to one feature of the herein proposed invention, the apparatusis so constructed as to ensure complete burning of the oil vapours,whereas the heat thereby released is used for additionally heating theloose material being dried.

In the course of heating the material does not contact with the fuelcombustion products, whereby oxidation of the material is obviated.

Rotation of the worm 3 promotes uniform heating and drying of thematerial.

The capacity of the proposed apparatus is controlled by the rotationalspeed of the disk feeder 14, depending on the initial condition of thematerial being dried.

The apparatus can operate in an automatic mode, by maintaining acontinuous drying temperature through varying the flow rate of gas fedto the burners 12 and 20 in response to the readings of the thermometer22.

The amount of underpressure or vacuum in the pipe 10 is controlled sothat evacuation of oil and moisture vapours through the holes 13, 18 and21 is carried out simultaneously with suction of air through thedischarging means 8. This enables to maintain burning of gas and oilvapours in the heating chamber 9, and cool the material as it isdischarged from the apparatus.

The loose material is heated in a counterflow of waste gases withoutdirect contact of the material therewith. This results in a substantialreduction in the temperature of the waste gases escaping from theapparatus, and therefore improves thermal efficiency of the apparatus.

Because the loose material being dried is not in extensive contact withwater and oil vapours due to their continuous evacuation from thematerial at the locations where they are formed through the openings 18to the interior 17 of the inner tube 2, the proposed apparatus ensures ahigher quality of drying. The absence of extensive contact between thematerial being dried and water vapours results in less pronouncedoxidation of the material, whereas the absence of extensive contact withoil vapours reduces carbonization.

Continuously maintained temperature conditions by automatically varyingthe feed of gas to the burners 12 and 20 in response to the readings ofthe thermometer 22 prevents overheating or underheating of the material,otherwise resulting, accordingly, either in oxidation of the material orexcessive content of moisture and oil therein.

The proposed apparatus is more fuel-efficient due to utilization of theheat produced by oil vapour burning, which affords a reduction in theamount of fuel gas consumed for the drying process.

The invention can fine application in metallurgy and other fields of theindustry for drying pulverulent materials, such as chips of cast iron,non-ferrous metals and alloys thereof.

We claim:
 1. An apparatus for conductive drying loose materialscomprising a housing (1) accommodating outer and inner tubes (2 and 4)arranged concentrically relative to each other, connected therebetween,and provided with worms (3 and 5) at their outer walls, charging anddischarging means (7 and 8) communicating with the interior of a dryingchamber (6) confined between the outer wall of the inner tube (2) andinner wall of the cuter tube (4), a pipe (10) of a suction means, and afurnace (11) with a burner (12) communicating with the interior of aheating chamber (9) confined between the outer wall of the outer tube(4) and inner wall of the housing (1), characterized in that in thevertical arrangement of the apparatus the inner tube (2) is capable ofrotation, whereas lower ends of the inner and outer tubes (2 and 4) areconnected by means of a flange (15) to a disk-type feeder (14) providedwith holes (13,21), the interior of the drying chamber (6) communicatingwith the interior of the heating chamber (9) by way of the holes (13) inthe disk-type feeder (14), whereas an interior (17) of the inner tube(2) communicates with the interior of the drying chamber(9) through theholes (21) in the flange (15), the furnace (11) being positioned betweenthe flange (15) and worm (5) of the outer tube (4), the dischargingmeans (8) occupying the bottom part of the apparatus.
 2. An apparatusfor conductive drying loose materials as claimed in claim 1,characterized in that the inner tube (2) has openings (18), and isprovided with a burner (20) mounted in the upper part of the inner tube(2).